Patent Literature 1 discloses an example of the shape of a separator core (hereinafter may be referred to as the “core”). When a separator is transported by a transport system such as a roller and continuously produced, the resulting separator is wound around this separator core to be supplied as a product.
The core disclosed in Patent Literature 1 has an outer cylindrical part around which a separator is wound, an inner cylindrical part which serves as a bearing for a shaft, and support parts which are connected to the outer cylindrical part and the inner cylindrical part (such support parts may be hereinafter referred to as “ribs”). The produced separator is supplied in the form of a roll, which is obtained by winding the separator around the outer cylindrical part.